Cracks in semiconductor wafers such as silicon wafers, which are materials used in fabrication processes of semiconductor devices, cause a great loss. There is accordingly an increasing need for wafers, for use in device fabrication, that are resistant to cracks.
In fabrication processes of semiconductors and liquid crystals, particularly, processes of dry etching, ion implantation, vapor deposition, and so on, increased processing temperatures, rapidly heating, and rapidly cooling are being promoted, and fabrication processes performed under vacuum and a dry condition are increasing. In addition, since enlargement of the diameter of substrates such as silicon wafers or glass substrates are advanced, impact resistance or the like is further regarded as important.
The cause of breakage of semiconductor wafers, in many cases, is that the edge of the wafers suffers a blow. It is accordingly important to evaluate the impact strength of a notch portion because the strength especially in the vicinity of the notch portion is low.
Since silicon wafers and the like are brittle materials, an evaluation technique for general materials increases variation in measurement. There are no commercially available standard instruments for evaluating and inspecting brittleness of the notch portion of the wafers. Such an apparatus as is disclosed, for example, in Patent Document 1 has been developed.